No4x4Yet

Since the formula has apparently changed since I learned it. we need to discuss this?

N20jeep

Its not the formula you're getting wrong. Its the application. When dealing with multiple coils like on a vehicle spring, the way you determine it changes.

A coil springs spring rate is determined by the overall movement of all the coils combined.

Example, lets say you have a coil spring with a spring rate of 100lbs per inch. And it has 10 coils, this means each of those coils will only need to move. 1/10" to equal the one inch drop, meaning it would take 10lbs per coil to equal that inch.

Now you take away one of the coils like you would by cutting a spring. Now you only have 9 coils. So instead of them only needing to move 1/10" each, they will now need to move 1/9"( which is more) to equal that same full inch of compression in the spring. Which means more pressure will need to be applied, since you now hace less coils to go the same distance. resulting in more OVERALL spring rate

No4x4Yet

You are right, but those are LIVE coils! This is why I emphasized ONLY cutting off DEAD coils! If you look at the coil there are 3-4 coils stacked on top of each other. These arent affecting the spring rate. Depending on the spring and number of dead coils you can cut more or less off without affecting the spring rate.

The coils at the top are stacked on top of each other. They arent gonna all umcompress while driving. You could remove 1-2 coils depending on the spring rate and suspension travel with now ill affects.

93XJLI

It seems I missed something

N20jeep

That is a progressive rate coil, Which you only referenced once. And I don't know why that was even brought into the debate. Most of that conversation that I read was about cutting standard single rate coils... like our factory coils and most aftermarket coils.

And cutting those will change overall spring rate

Coastal

you and I both

No4x4Yet

I could have sworn I had single rate springs on my mustang that bunch up at the bottom, but maybe Im wrong? Ill have to look into that.

N20jeep

It would have been progressive that does that. Single rate springs collapse equally throughout the coils

xj_maniac_newb

BNJeepsta

Is this going on again or is this the same guy who just doesn't get it?

93XJLI

im still confused

N20jeep

Uh, GO AWAY!

hankthetank

It would take more force to compress one coil, one inch, than ten coils one inch. It's all about load distribution.

emptypockets

From Lefthander Chassis 2010 catalog.

No4x4Yet

I have have my springs mixed up here which would make you right here. That doesnt mean cutting every spring is bad, as I said from the start cutting off DEAD COILS, will not affect the spring rate. It doesnt matter what kind of spring it is, if you cut live coils you will change the spring rate.

As for the original topic of the discussion the F-150 springs, arent those overly stiff to begin with? So cutting a coil or two to get the desired height and a lower, more reasonable spring rate would actually be beneficial, no?